Fluorosilicone polymers are well known in the industry due to excellent physical properties. However, expense of manufacture and raw materials restricts the use of these polymers to tightly specified applications where, for example, solvent resistance is essential.
Fluorosilicone polymers are produced by first taking the appropriate fluoro-substituted diorganodichlorosilanes and hydrolyzing them. The hydrolyzate is then taken, its acidity reduced to the appropriate level, and it is separated from excess water. Then there is added to the purified hydrolyzate the appropriate amount of alkali metal hydroxide catalyst and the hydrolyzate is heated at temperatures of about 200.degree. C. or more so as to preferentially distil overhead fluoro-substituted cyclo trisiloxanes. In fluorosilicone chemistry it has been found that cyclotrisiloxanes react more readily in forming polymers than do the corresponding cyclotetrasiloxanes. Also, it is known in this chemistry that sodium based catalysts are preferable over potassium due to the necessary and appropriate basicity to optimize yield. Accordingly, there is taken the appropriately formed cyclotrisiloxane and there is added to them a basic sodium polymerization catalyst with the appropriate amount of end-stopping agent and/or molecular weight modifier and the resulting mixture is heated at elevated temperatures so as to form the desired diorganopolysiloxane polymer. Heating may continue for a time period of from 1/2 to 24 hours, equilibrating the polymer to the desired molecular weight.
It is desirable in fluorosilicone chemistry to increase the effectiveness of the sodium polymerization catalyst in order to reduce the sodium salt residue as a by-product and to reduce time required to equilibrate the polymer to the desired molecular weight. Further, due to disparity in the reactivity of many end-capping agents and cyclotrisiloxane, it is desirable to provide for greater initial end-capping action. Finally, it is desirable to provide a sodium catalyst which does not introduce hydroxy groups or other often undesirable groups into the production of fluorosilicone polymer.